Bachelor star Vienna Girardi has denied reports that she was unfaithful during her relationship with ex-fiance Jake Pavelka.

In a new clip from their upcoming interview with Chris Harrison - aired on today's GMA - the couple are seen discussing the allegation that Girardi cheated on Pavelka with a man named Greg.

"First of all, I didn't even meet Greg till 9 o'clock at night at the charity event at a hospital," says Girardi. "The only thing you have is me dancing not even nine seconds in a group of people and I'm not even with him."

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Pavelka then asks why she is raising her voice, prompting Girardi to respond: "Because you are the biggest, fake liar I've ever met in my entire life! There is nothing! I hardly even know that guy. I went to a charity event, met him with a group of people, and the next day he invited everybody out. I went with my girlfriend, he was there with three other girls. That's the entire story!"

Pavelka then asks, "Who was the guy you had on Saturday night at the apartment?" before the clip cuts out.

The former couple became engaged on the season finale of the ABC romance reality show's 14th instalment, but announced that they had split last week.